Tuesday, April 27, 2010

Whilst on a sojourn recently in Yorshire I took a trip to York only to come upon a goose. The greylag goose (Anser anser). I was walking along a canal with friends of mine and there it was. Later I saw two more along with eight offspring.

Greylag goose (Anser anser)

Greylag geese are monogamous, exist in a female-bonded social system, similar to primates, and their fledged offspring stay with them until the next breeding season. Dominance rank in flocks of geese is determined by the active social support family members or pair partners give to each other. Parents provide active assistance for their offspring in encounters with other members of the flock but females and juveniles of several species of geese involved in agonistic behaviour were more successful when a male partner or parent was present but did not actively interfere. If parents fail to produce young, subadults (a bird with some adult traits but not yet sexually mature) may rejoin them in summer after molting is completed and thus form a 'secondary family' and this may be seen as an alternative tactic for the subadult geese where they associate with former allies when no suitable mate is available. Scheiber et al. suggest that retaining a family unit might allow both the parents and the offspring to preserve a high social status and also enjoy the benefits of a social alliance such as the males winning agonistic interactions and the females having a decreased level of CORT (lower stress levels). [Isabella B.R. Scheiber, Kurt Kotrschal, Brigitte M. Wei[ss], Benefits of family reunions: Social support in secondary greylag goose families, Hormones and Behavior, Volume 55, Issue 1, January 2009, Pages 133-138].

Greylag goose family

Whilst taking the above picture the nearest adult goose hissed quite loudly at me. I only wanted to say 'Hello'. Although greylag geese can be hand-raised and see humans as allies in their agonistic interactions this was certainly not the case here. I was not part of their family.

Monday, April 26, 2010

Rare in the rest of Ireland, the pretty Common Toadflax (Linariavulgaris) is frequently spotted in the South to Southeast of the country. Producing its yellow flowers from June to October, it can be found on roadsides, waste ground, grass banks and cultivated fields growing to a height of 60 cm. Its status as an Irish native is questionable, however it does help to support long-tongued pollinators such as Bombuspascuorum and B. hortorum by the provision of valuable nectar (Corbet etal., 2001 Annals of Botany 87 pp. 219-232). Taxonomically, L. vulgaris was traditionally placed in the family Scrophulariaceae. Recent phylogenetic analysis of DNA regions from members of the family now places the genus Lniaria within the Plantaginaceae (Albach et al., 2005 American Journal of Botany 92 pp. 297–315).

L. vulgaris is used in traditional medicine as a laxative, as well as for the treatment of inflammation of the bladder, skin rashes and haemorrhoids. Its perceived activity is due to the presence of iridoidglucosides (such as antirrinoside and procumbide) in the stem, leaves and roots of the plant (Ilievaetal., 1992 Phytochemistry 31 pp. 1040-1041).

Unfortunately, what is seen as an attractive margin wildflower by some, has become a pest to others. L. vulgaris was introduced to the USA as an ornamental garden plant, but soon escaped into the wild and was recognized as a major agricultural weed in 1758 by the botanist John Bartram (Mack, 2003 Annals of the Missouri Botanical Garden 90, 77–90). Bartram stated that “neither the spade, plough nor hoe can eradicate it, when it is spread to a pasture”, undoubtedly due to the extensive creeping root system of the plant. The problem persist today, however the introduction of the weevil Mecinusjanthinusas a biological control agent into both the USA and Canada has helped to control L. vulgaris populations (McClay and Hughes, 2007 Biological Control 40 pp. 405-410).

Hymenacidon perleve is a Demiosponge of the family Halicondridae commonly seen in the intertidal areas of Irish shores. As a species, it has been recorded in the Atlantic, Pacific and Mediterranean as well as the Southern coast of Africa. It is a very conspicuous sponge, being a vibrant orange colour.

It has recently been mined as a source of new actinobacteria, which have the potential to provide novel bioactive compounds, such as antibiotics. Actinobacteria produce over half of the bioactive compounds in the Antibiotic Literature Database (Lazzarini et al., 2001 Antonie Van Leeuwenhoek 79 pp. 399-405). Zhang et al. (2006, Antonie van Leeuwenhoek 90 pp 159–169) report on the isolation of 106 actinobacteria from H. perleve from the China Sea. 74% of the isolates were Streptomyces spp. and three strains isolated are candidates for new species.

H. perleve has also shown remarkable ability to remove pathogenic bacteria from ambient water. Sponges filter the water passing through them and feed off the subsequent filtrate. Due to this feeding mechanism, sponges have shown a high capacity to reduce microbial pollution associated with faecal contamination (Claus et al., 1967 Nature 216 pp. 712–714), a common problem in aquaculture systems. H. perleve has been used to control bacterial levels in turbot water systems (Zhang et al., 2008 Journal of Biotechnology, 136, pp. S685). Fu et al. (2008, Journal of Biotechnology pp. S548–S557) has even shown with work on a non infectious Escherichia coli and infectious Vibrio spp. that infectious bacteria can be discriminated by 14-3-3 gene expression of H. perleve.

Friday, April 23, 2010

Plant parasitic nematodes are major agricultural pest. For example, potato cyst nematodes (Globodera pallida and Globodera rostochiensis) alone are estimated to cause €350 million worth of losses annually in the EU alone. The use of fumigants (such as methyl bromide) to control nematode numbers has been curtailed due to public health concerns.

A very successful alternative to the use of such nematicides is the application of organic soil amendments to suppress nematode numbers. Examples of these organic soil amendments include plant preparations of Neem (Azadirachta indica) and Asteracea, organic manure and chitinaceous materials. In a recent study (Oka, 2010 Applied Soil Ecology 44 pp. 101–115) it was shown that, while interactions between organisms in the rhizosphere are quite complex, possible mechanisms such as release of nematicidal compounds from soil amendments, generation of such compounds during degradation and enhancement of antagonistic mico-organisms in the soil among others all combined to reduce nematode numbers.

Whether it be nestled in a gap in stone work, adding colour to roadside ditches or blanketing forest floors, the Lesser Celandine (Ranunculus ficaria) is in its prime at the moment. A relative of the buttercup, it is unrelated to its name sake the Greater Celandine (a member of the poppy family). In the past, it was used as a treatment for piles, as described by Nicholas Culpeper in his Complete Herball (c. 1653):

"The leaves are antiscorbutic and the root reckoned a specific if beat into cataplasms and applied to the piles."

This earned the plant the name Pilewort, its name derived from the shape of the root. Its medicinal properties were discredited about fifty years later by Lindley who stated:

"Confident as are these assertions (those of Culpeper and others), yet the use of the plant is all but discontinued in the present day, medical practitioners properly looking for sounder principles than those derived from the doctrine of similitudes."

It was however still being advocated as a cure for piles in 1901 (Birmingham Medical Review, May 1901), but consumption in herbal remedy has been shown to result in necrotizing hepatitis (Strahl et al., 1998 Deutsche medizinische Wochenschrift 123 pp. 1410–4).

The classification of R. ficaria as such is in question, as several authorities consider it to be a genus of its own, Ficaria (Hörandl et al., 2005 Molecular Phylogenetics and Evolution 36 pp. 305-327).

Monday, April 19, 2010

Polychaetes play an important role in the functioning of many marine communities. This is due to a number of factors, such as their proliferation within certain habitats (such as benthic regions) and the diversity of their feeding modes. (Giangrande et al., 2005 Marine Pollution Bulletin 50 pp. 1153–1162). These range from surface deposit, suspension, mud swallowing, carnivory and herbivory to in a few species even parasitism.

Many burrow into the sediment both for protection against predation and also in search of food, and others actively swallow mud and deposited particulate matter in order to obtain their nutrition. Others are tubiculous and some of these species are highly gregarious (Hutchings, 1998 Biodiversity and Conservation 7 pp. 1133-1145).

Below are some common polychaete species to be found on Irish seashores.

The Amber Snails (Succineidae), are a family of snails with thin-walled, glossy translucent shells with large body-whorls and very short spires. They are typically found in wet habitats and some are amphibous. Five species are found in Ireland, such as Oxyloma pfeifferi, Pfeiffer's Amber Snail, pictured below. O. pfeifferi has in fact been identified as a major pest of hardy nursery stock by horticulturalists, with losses of €3.5 - 4 milion being reported (Schuder et al., 2004 Crop Protection 23 pp. 945–953).

Pfeiffer's Amber Snail, Oxyloma pfeifferi

Succineidae have also been identified as another potential risk to another agricultutal sector. The liver fluke, Fasciola heptica, is an internal parasite of livestock that causes €25 million worth of loss to Irish farmers yearly with deaths and lost production, due to lowered weight gains, milk production and fertility. In 2008, deaths due to acute and chronic fasciolosis accounted for 20.5% of diagnosed causes of death in adult sheep in Ireland (Irish Regional Veterinary Laboratories Surveillance Report 2008). F. hepatica requires an intermediate molluscan host to complete its life cycle and worldwide species from the genera Lymnaea, Galba, Pseudosuccinea and Stagnicola act as these hosts. In Ireland and the UK the water snail Galba truncatula is the recognised host of F. hepatica. However, a study by Relf et al. in 2009 (Veterinary Parasitology 163 pp. 152–155) discovered a Succineid as an alternative intermediate host of F. hepatica. They found that in a hill and mountain grazing system, where the acidic soil conditions would not support populations of G. trunculata due to sufficient calcium for shell developement, infection among the sheep herd was 63.6%. Using PCR analysis of cytochrome c oxidase subunit 1 gene of F. hepatica, 79% samples of the same Succineid species showed presence of the fluke.

Thursday, April 15, 2010

The intertidal area of the shoreline is subject to high intensity of wave action, with the result that many of the flora and fauna present have had to adapt to this often harsh environment. Molluscs and arthropods present have tough, durable shells (e.g. mussels, whelks, sea slaters) and/or cling tightly to the rocks (e.g. limpets, barnacles) while algae present is tightly bound to the rock by holdfasts. Even the seemingly soft bodied anemones have a strong attachment to the rock via their pedal discs.

It is therefore quite surprising to find an animal in quite abundance that has neither of these attributes. Anurida maritima is a small (c. 3 mm), blue coloured springtail (Collembola) that scavanges for dead or dying matter in the intertidal zone. Interestingly, it cannot hypo-regulate its ionic concentration in water with less than 50% salt water, meaning it cannot survive in fresh water conditions. Collembolans are of terrestrial origin, meaning A. maritima is an amazing example of an animal of terrestrial origin that has become physiologically tied to a saline environment (Witteveen et al. 1987 Journal of Insect Physiology 33 pp. 59-66).

What is even more startling about A. maritima is its ability to walk on water. Its body is covered in hydrophobic hairs that allow it to walk with some ease across intertidal pools in search of food.

Wednesday, April 14, 2010

Horsetails are represented by only one extant genus (Equisetum) but many extinct species are represented in the fossils record. Taxonomically, they are placed in the class Equisetopsid (Sphenopsida) order Equisetales and family Equisetaceae. Equisetopsids first appeared in the Devonian period but, attained their maximum diversity during the Carboniferous. From the Carboniferous to the present day, the group has experienced a gradual decline to where today just 15 species are recognised (Taylor et al. (eds), 2009 Biology and Evolution of Fossil Plants pp. 329-382). They are characterised as having whorled, gapped stems and connate, whorled leaves. Features of their spermatazoids group them with ferns, with their closest phylogenetic relative being the Marattiopsids (Smith et al., 2006 Taxon 55 (3) pp. 705–731)

Vegetative stem of Equisetum arvense

In Ireland, the most abundant horsetail species is the Field or Common Horsetail (Equisetum arvense). It favours wet soil conditions and is most common on or near river banks, but can establish on arable land becoming a troublesome weed.

At this time of the year, the green stems of E. arvense are nowhere to be seen, having died away during the winter. Instead, pinkish-brown stems are visable and will be until June. These are the fertile stems of the horsetail. The cone at the top of the stem (the strobili) is comprised of peltate sporangiophores that bear the sporanhia.

Tuesday, April 13, 2010

The Green Worm, Eulalia viridis ia a marine polychaet worm of the family Phyllodocidae that inhabits intertidal pools. At one time thought to be a predator it is now know to scavenge mainly on damaged, dead and decomposing material, mainly barnacles and mussels (Emson, 1977 Journal of the Marine Biological Association of the UK 57 pp. 93-96).

Monday, April 12, 2010

Of the 3000 centipede species described world wide, each one has an odd number of segments, ranging from 15 to 191. Chipmanetal. (Current Biology 14 pp. 1250–1255, 2004) report that variation in segment number is caused by variation in the number of cycles of a primary segmentation oscillator, each cycle of which generates two segments.

Interestingly, the genes responsibly for this double segmental periodicity in centipedes (odd-skipped and caudal) are homologues of Drosphilia genes (Nüsslein-Volhard and Wieschaus, 1980 Nature 287 pp. 795-801). These genetic similarities may be a result of evolutionary convergence or could be an indication of a common ancestor of both flies and centipedes (Damen, 2004 Current Biology 14 pp. R557–R559). This may help shed some light on the relatedness of the myriopods to the other arthropod groups.

Friday, April 9, 2010

Actinia equina, the beadlet anemone, is the most common anemone to be found in Irish and European waters. In fact, its range extends all over the Mediterranean and even down the coast of Africa. Most conspicuous at low tides when the solitary, deep red polyps are visable clinging to rockfaces, A. equina can be an aggressive individual, with a full arsenal of toxins at its disposal.

Actinia equina exposed at low tide

It is named after the circle of blue, bead-like structures found at the base of the feeding tentacles. These are the acrorhagi, organs found only on certain species of the Actiniidae family. They are small sacs full of cilia-covered nematocysts that the beadlet anemone uses to subdue and kill prey. The acrorhagi are dilated by absorbing seawater and pressed against the victim. Outer pieces of the acrorhagi stick to the prey, into which the nematcysts are discharged (Shiomi 2009, Toxicon 54 pp. 1112–1118).A. equina reproduces both sexually and asexually by parthogenesis, with reproductive modes varying at different sites. Non-clonal anemones can be quite aggressive to each other, and this has been shown to be linked to the colour of pedal disc colouration (Brace et al. 1979 Journal of Animal Behavour 27 pp. 553). Three morphs exist on Irish shores, U, M and L morphs (see table). This variation in reproductive modes, coluration and aggression suggest that A. equina may not be a single species at all but may be several cryptic species, subspecies or morphs (Chomsky et al. 2009 Journal of Experimental Marine Biology and Ecology 375 pp. 16–20).

Morph

Pedal Disc Colour

Location

U

Dark red

Upper shore

M

Light red

Mid-shore

U

Grey-green

Lowershore

As can be seen from the table, the U morphs are the most aggressive of the three. The reason for this lies in they fact that they populate the verticle sides of gullies, where wave action provides a large supply of food. Competition for this resource would therefore be fierce, promoting aggression. The weapons used by A. equina in this aggression are peptide toxins contained in the nematcysts which block sodium and potassium ion channels (e.g. acrorhagin I and II).

Liverworts are classified as bryophytes, and are distinguished from the other members of this order (mosses and hornworts) by having either flat-lobed leaf-stem structures or small leaves in rows of three. They can be found on tree trunks or growing on exposed soil, often in association with mosses. As such, they can become a troublesome weed in some horticultural situations (e.g., Lunularia cruciata).

Lunularia cruciata

Liverworts are ungrazed by animals, fungi and bacteria. This suggests that they contain antifeedant phytochemicals as morphologically they appear quite lush and succulent. Further evidence for their phytochemical activity can be seen in the history of the use of liverworts (along with other byrophytes) to cure cuts, burns and external wounds and as treatment for bacteriosis, pulmonary tuberculosis, neurasthenia, fractures, convulsions, scalds, uropathy, pneumonia and neurasthenia. While some of this may be attributed to the doctrine of signatures, they erroneous idea that plants shaped like body parts copuld be used to treat said body part research has shown that 700 terpenoids and 220 aromatic compounds have been isolated from liverworts, many of which show interesting biological activity. Liverworts are a greater source than the other Bryophytes of biochemicals as they contain cellular oil bodies, which are composed of lipophilic terpenoids and aromatic compounds (Asakawa(2001), Phytochemistry 56 pp. 297-312).

An example of one such phytochemical is Marchantin A. This bis(bibenzyl) is commonly found in Marchantiales species such as Marchantia polymorpha and shows antifungal, antimicrobial and muscle relaxing and cytotoxic activities.

Marchantia polymorpha

Due to the lack of a fossil record for bryophytes, the evolution of liverworts is unclear. However, two theories exit. The first is the progressive theory that suggests that bryophytes arose from algae and in turn gave rise to the pterioophytes (ferns and their allies such as horsetails and quillworts). The second (the reductive theory) suggests that green algae dave rise to primitive ancestor of vascular plants from which both the bryophytes and pteridophytes arose. Currently, researches at the Tokushima Bunri University in Tokushima, Japan are attempting to solve this riddle by examining the phytochemical links between the two orders.

Thursday, April 8, 2010

The call of the cricket is produced by the male of the species by rubbing a stiffened vein “plectrum” of one wing over a toothed vein “file” of the other wing. This creates sound waves because of vibrations of the harp area in each wing. A sound pulse is produced by each closure of the wings. A chirp results from three to five pulses made in rapid succession. Interestingly, in the field cricket the chirp is temperature dependent affecting not only the chirp duration but also the period and frequency. (Communicatory Constraints on Field Crickets Gryllus bimaculatus Calling at Low Ambient Temperatures J. W. Van Wyk, J. W. H. Ferguson J. Insect Physiol. Vol. 41, No. IO, pp. 837-841, 1995)

I observed the Mediterranean field cricket (Gryllus bimaculatus) while on vacation in Argeles, France in 2009. He appeared to be very fond of my beach towel, either for the moisture or the shelter.

The family Clausiliidae (door snails) are characterized by a sinistral shell that is often ribbed and fusiform or spindle shaped with a tapering spire forming a large number of whorls (Molluscs, Vaclav Pfleger, 1999 pp.102). They feed mainly on algae and lichens and often can bee seen emerging from crevices in dark damp areas such as rock faces and heavily mossed tree trunks.

The Craven Door Snail, Clausilia dubia

However, door snails and the non-marine molluscs of Ireland as a whole are under threat. Of the 150 species present, two are considered to be regionally extinct, five critically endangered, fourteen endangered, twenty-six vulnerable, six near threatened, and the rest of least concern, or data deficient (Red List of Non-Marine Molluscs 2009, Byrne et al.). Ireland’s non-marine molluscan fauna is of international importance. Ten species have populations of significant international worth, having large proportions of their global population in Ireland.

Of the Clausiliidae present in Ireland, two species are vulnerable (Balea perversa and Cochlodina laminata) while another two of least concern (Balea heydeni and Clausilia bidentata). Loss of these species could have an unknown knock on effect on the ecology of the island of Ireland.

Thursday, April 1, 2010

And so to Currabinny woods, in search of lichens. Remembering my old lichen groups from college (and looking them up on the Internet as a reminder) Crustose, Foliose and Fruticose, I thought the identification would be a doddle. Not quite so.
Lichens are fungi that form stable self-supporting associations with either green algae or cyanobacteria. In lichens the fungus (mycobiont) is distinct from its free-living relatives both morphologically and in the production of unusual chemicals and is incapable of independent existence. The thallus, mostly consisting of the fungal hyphae, envelop the individual cells of the algae (photobiont) and it is the configuration of this thallus, crust-like (crustose), leaf-like (foliose), scaly (squamulose) or bushy (fruticose) that gives the first level distinction. Lichens can lie dormant in a dessicated state allowing them to survive the harshest habitats on Earth but they are extremely sensitive to air pollution. (The Diversity of Living Organisms R S K Barnes, 1998 Blackwell Science p124)

The first 6ft of different tree species was surveyed for different species of lichens.

The following observations were made:

The beech tree (Fagussylvatica). On this tree we found a crustose lichen called Lecidellaelaeochroma f. soralifera. Also present was Pertusariahymenea(Pore lichen) and Phaeographisdendritica.

Beech tree (Fagussylvatica)

Phaeographisdendritica

Lecidellaelaeochroma f. soralifera with his friend, the beetle (Order Coleoptera)

Pertusariahymenea

On a birch tree (Betulapendula) we found Leprariaincana(Dust lichen).

Silver birch (Betulapendula)

Leprariaincana on silver birch

On a fallen beech tree was the foliose lichen Parmotremaperlatum(Ruffle lichen), a woodrush (Luzulasylvatica) and the moss Polytrichum commune (see previous blog-entry on this moss).

On another fallen tree, this time a Japanese larch (Larixkaemferi), were Parmotremaperlatumagain and two fruticose lichens Usneasubfloridana(Beard lichen) and Ramalinafarinacea(Farinose cartilage lichen). These types of lichens were higher up in the tree but as it had fallen we were given the opportunity of photographing them up close.

Japanese larch with pink female flower

Usneasubfloridana

Ramalinafarinacea

On an oak tree (Quercussp.) we had more Pertusariahymeneaand some Leprariaincana.

Oak (Quercussp.)

Pertusariahymeneaon oak tree

On Scots pine (Pinussylvestris) we had more Leprariaincana.

Scots pine (Pinussylvestris)

Leprariaincana

Overall the most common lichen, present on three of the tree species was Leprariaincana. This lichen species is found on shaded trees and this would be the case for a lot of the Currabinny trees. Or maybe we just like the quiet places.
We also saw a few varieties of fungus, one of which is an old friend of mine, Trametesversicolor. Another favorite was the plant Montbretiaor St. Anthony's lily (Crocosmiaxcrocosmiiflora) which we had to confirm by unearthing its bulb (the woodrush had no such bulb) as none of its orange flowers were yet visible. We shall have to wait until July.

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We at the 21stcenturynaturalist hope to engage and provoke interest with our natural history based blogs.
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